Nitrogen is one of the contributors of greenhouse gases (GHG). In ruminants, more than 60% nitrogen was excreted in feces and urine during the animal life. Therefore, the faster the animal can be slaughtered the less nitrogen excreted. The aimed of this study to evaluate the decrease of nitrogen emissions by using early fattening in sheep after weaned. Thirty Thin Tailed lambs (aged 4 months; 13.70± 1.93 kg of BW) were used in this study. The feed was pelleted complete feed that contained 14% - 18% crude protein (CP) and 60% - 70% total digestible nutrients (TDN). The nitrogen emission was analyzed from urine and feces. Feed, feces, and urine were collected during 7 days using the total collection method. Nitrogen (N) was analyzed using Kjeldahl method. The data were analyzed using descriptive analysis. The results showed that lambs fattened during 3 months had 24.32 kg of slaughter weight, with an average daily gain (ADG) was 126.4 g/d, which is in traditional farmers in Indonesia required at least 12 months to achieve 24 kg of slaughter weight. It indicated that early fattening can be faster 5 months than that of the traditional farmer. In this study, the daily N emissions from feces and urine were 13.43 g/d, the emissions of N2O was 0.27 g/d. Those results could be calculated total emissions of N and N2O between early fattening (7 months) and traditional farmer (12 months). The total emissions of N were 2.82 kg vs 4.83 kg, N2O; 56 g vs 96 g, respectively. Based on the result, it could be concluded that shortening rearing period in sheep can reduce the emissions of N and N2O until 41%.